The present invention is related to the Universal Mobile Telecommunications System (UMTS) and, more particularly, to Packet Data Protocol (PDP) context Quality of Service (QoS) parameters.
Quality of Service in UMTS has been the subject of an ETSI Technical Report UMTS 23.07 v0.4.0 (1999-04), which describes various QoS parameters related to throughput/bitrate, including maximum bitrate, which is defined as the maximum number of bits delivered by UMTS at a Service Access Point (SAP) within a measurement period, divided by the duration of the measurement period. Also, a guaranteed capacity minimum bitrate is defined as a guaranteed number of bits delivered by UMTS at a SAP within a measurement period (provided that there is data to deliver), divided by the duration of the measurement period. A UMTS Terrestrial Radio Access Network (UTRAN) overall description can be found in ETSI Technical Specification TS25.40 v1.0.0 (1999-04).
The maximum bitrate can be used to make code reservations in the downlink of the radio interface. Its purpose is to limit the delivered bitrate to applications or external networks with such limitations. The guaranteed bitrate may be used to facilitate admission control based on available resources, and for resource allocation within UMTS. Quality requirements expressed by e.g., delay and reliability attributes only apply to incoming traffic up to the guaranteed bitrate.
When the system becomes capacity restricted, the interference level in the radio interface will grow, and errors will occur to data packets. The problem is that errors start to occur more often for those users that are at their maximum (allowed or equipment limited) power, including those who comply with their traffic contract, i.e., the errors affect not only those whose used bitrate is more than xe2x80x9cguaranteedxe2x80x9d, but all users. In simple terms, the users at the cell edge start to suffer first. The process is not random, but neither is it connected to the used vs. guaranteed bitrate if no control mechanism is introduced.
The invention provides a control mechanism to decrease the data rate used by the users that are exceeding their guaranteed rate in the presence of errors.
According to a first aspect of the present invention, a method for use in a universal mobile telecommunications system (UMTS) having a plurality of radio access networks (RANs) accessible by mobile stations in their vicinity, said RANs connected to a UMTS core network, wherein each of said RANs allocates capacity in response to demand for capacity from said mobile stations in their vicinity, said method comprising the steps of:
each RAN allocating, for each connection to an associated mobile station, a guaranteed capacity minimum bitrate as well as a non-guaranteed maximum bitrate and communicating said guaranteed bitrate and said non-guaranteed bitrate to said associated mobile station along with an error rate threshold; and
each associated mobile station determining an error rate, comparing said error rate to said error rate threshold, and freely using a bitrate between said minimum bitrate and said maximum bitrate for so long as said error rate does not exceed said error rate threshold, but in the event said error rate exceeds said error rate threshold, using a reduced bitrate until said connection is terminated or said error rate no longer exceeds said error rate threshold and again freely using a bitrate between said minimum bitrate and said maximum bitrate beginning a random time period after said error rate no longer exceeds said error rate threshold.
In further accord with the first aspect of the invention, said step of using a reduced bitrate is carried out for connections carrying plural bearer services by first reducing said bitrate for a selected one of said plural bearer services and then using a reduced bitrate for one or more others of said plural bearer services if said error rate remains above said threshold.
According to a second aspect of the present invention, a method for use in a universal mobile telecommunications system (UMTS) having a plurality of radio access networks (RANs) accessible by mobile stations in their vicinity, said RANs connected to a UMTS core network, wherein each of said RANs allocates capacity in response to demand for capacity from said mobile stations in their vicinity, said method comprising the steps of:
each RAN allocating, for each connection to an associated mobile station, a guaranteed capacity minimum bitrate as well as a non-guaranteed maximum bitrate and communicating said guaranteed bitrate and said non-guaranteed bitrate to said associated mobile station;
each RAN determining an error rate, comparing said error rate to said error rate threshold, and permitting free use of said connection at a bitrate between said minimum bitrate and said maximum bitrate for so long as said error rate does not exceed said error rate threshold, but in the event said error rate exceeds said error rate threshold, commanding use of said connection at a reduced bitrate until said connection is terminated or said error rate no longer exceeds said error rate threshold and again permitting free use of said connection between said minimum bitrate and said maximum bitrate beginning at a selected time after said error rate no longer exceeds said error rate threshold.
In further accord with the second aspect of the invention, said step of commanding use of said connection at a reduced bitrate is carried out for connections carrying plural bearer services by first commanding use of said connection at a reduced bitrate for a selected one of said plural bearer services and then only commanding use of said connection at a further reduced bitrate for one or more others of said plural bearer services if said error rate remains above said threshold.
These and other objects, features and advantages of the present invention will become more apparent in light of the detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawing.